The present invention relates to pneumatic brake-boosters, and more particularly to their fastening on a fixed part of a vehicle or the fastening on them of a master cylinder.
Pneumatic boosters are well known in braking technique, and typically comprise a casing on which is formed a well housing an operating valve means, a first wall having at least one opening cooperating with means for fastening the casing on a fixed part of a vehicle, a second wall having at least one opening cooperating with means for fastening a master cylinder on the casing, at least one annular member being disposed in the casing, against a wall.
In conventional manner the fastening means consist of wide-headed mounting screws whose heads are disposed inside the casing, while the threaded portion of the screw extends outside the casing to receive a nut fastening the casing to a fixed wall of the vehicle or to the master cylinder.
Numerous problems arise in connection with the holding of the screwhead in the casing before its installation, and have been solved by fitting additional parts inside the casing, by crimping the screw on the casing walls, and so on.
Other problems arise in the preventing of the screw, once in place, from turning when the nut is screwed on, and have been solved by giving an antirotational shape to the screwheads as disclosed by GB-A-2 087 016.
All these solutions lead to complex, expensive constructions, which in addition entail the disadvantage of increasing the weight of the booster.